Low-water alarm



Jan. 18, 1927.

Normgu.

, 1,615,061 R. L. BADGER LOW WATE ALARM Filed Feb. 10. 1926 WATER LEVELTo? 1- SATuRATEo GTEAH Lowest SAFE WATER LEVEL WATER GLAs Low EST SAFEWATER LEVEL my 75 WNW? a; mm 19 17M QMMW Patented Jan. 18, 1927.

UNETED STATES ROY L. BADGER, OF YOUNGSTOWN, OHIO.

LObV-WA'IER ALARM.

Application filed February 10, 1926.

The object of this invention is to provide a reliable low water alarmadapted to indicate certainly and promptly the fact that the water levelin the boiler has descended to a dangerous point. My alarm is especiallywell suited for locomotive boilers and has been developed particularlyto enable certainty of operation, notwithstanding the sudden changes inwater level due to the rolling, tipping and plunging of the locomotiveon the track and the irregularities consequent upon grades, sudden stopsand ex treme demand put on the boiler in starting heavy trains.

It has been customary to locate the temperature controlling element inmost water alarms in a region just above the lowest sate level of thewater, so that such element will be subjected to steam action when thewater descends to a danger point. My observations and experiments haveindicated that there is immediately above the water a more or lessdefinite layer of heavy wet saturated steam, which has considerablecapacity for conducting heat, and I have found that I can produce muchmore accurate results by arranging the device so that the heat about thetemperature responsive element is concentrated in a region which is notonly above 30 the permissible low water level, but is above the layer orwet saturated steam when the water is at such low level. Accordingly myinvention includes a temperature responsive element to control the alarmoperation and means for transmitting heat to such element from the tirebox so arranged as to concentrate the heat in a region which is abovethe layer of heavy saturated steam which will lie over the water whenthe water has dropped to a dangerous level.

My invention includes not only the above described characteristic 0Tlocation of the concentrated heat region, but the peculiar i hereinafterdescribed whereby I ac- ."h such location tor concentration of heat icause the alarm to remain in operation until the water has descended tothe dangerous level, and to thereupon operate with promptness andcertainty. My inven tion also includes the particular embodiwent ctthese features illustrated in the c 'awing which enables convenientinstallation and adjustment to meet conditions which vary with differentlocomotives.

I prefer to use as the pressure controlling element a thermo-couplemounted in a suit- Serial No. 87,202.

able casing which is installed in a recess in the heat transmitting plugin the region of heatconcentration. The means for positioning suchdevice, and allowing its ready removal for inspection, are alsocomprised within my invention.

My invention is hereinafter described in connection with the embodimentillustrated in the drawings, while the essential novel features aresummarized in the claims.

In the drawings, Fig. 1 is a side elevation of a portion of a locomotiveequipped with my low water alarm; Fig. 2 is vertical section through thelow water alarm, part of the construction being broken awayintermediately; Fig. 8 is a horizontal section through the heattransmitting plug, as indicated by the line 33 on Fig. 2 lookingupwardly; Fig. 4i is a cross-section of the device in the region of thethermo-couple; Fig. 5 is a tragmentary detail, on an enlarged scaleillustrating the threaded engagement of the plug and shell.

As shown in Figs. 1 and 2 of the drawings. 1.0 indicates the crown sheetand 11 the root sheet of a locomotive boiler, and 12 a stand ard gaugeglass in communication with the water and steam spaces between suchsheets. The casing or external member of my alarm includes a tube whichextends through the root sheet to a point adjacent the crown sheet andit is tightly connected with a bushing 2]. screwing into the crownsheet. A suitable stufiing box carried by the root sheet and surroundingthe tube clamps it tightly thereto.

As shown, the tube 20 is externally threaded near its lower end andscrews into an internally threaded recess in the bushing 21, thereafterthe tube and bushing are welded together, preferably by the applicationof metal from arc welding, as indicated by the fillet 24, thus securingthese parts permanently together. The bnshing has tapered externalthreads by which it may make a tight connection with the crown sheet.The lower end of the bushing is provided with notches 26, enabling it tobe turned by a spanner wrench.

The stufiing box referred to carried by the roof sheet, comprises abushing having a tapered thread engaging the roof sheet, an internallyflanged nut 31 screwing onto the bushing and packing 32 between the nutand aninclined shoulder in the bushing. The opening of the roof sheetwhich the bushing occupies is of a larger diameter than the exteriordiameter of the bushing 21. This enables the bushing 21 to bepermanently secured to the tube before the same is installed then thetube with its bushing to be passed through the opening of the roof sheetinto registration with the opening of the crown sheet; then theapplication of a spanner wrench to the notches 26 to turn the parts intoplace without subjecting the connection between the tube and bushing 21to strain. After the tube is thus mounted in the crown sheet, thebushing 30 is applied to the roof sheet and the packing completes thisportion of the installation.

It will be observed that the interior of the tube 90 has a continuousthread 22 extending from the lower end to a considerable height in thetube. This thread adjustably carries a. large copper plug which standswithin the tube 20 and for the most part is free from it but has anenlarged zone 41 externally threaded to engage the internal threads 22near their upper region. The region of the threaded engagement of theplug with the tube is so located that it will be substantially at thebottom of the dry steam when the water level is at the bottom of thegauge glass.

The lower end of the plug 40 is preferably made angular so that it maybe readily turned by a wrench to thus adjust it up or down the tube. Thedrawing illustrates this inner end of the plug square. Such portion ispreferably encased by some material tougher than copper, as, forinstance, cast iron. Such casing, which may be readily cast about thecopper core and is illustrated at 43 by the different section lining inFigures 2 and 3, protects the head from the fire box gases and fromdamage by the wrench.

The copper plug 40 has in its upper portion a recess d5 leadingdownwardly from the upper end. This recess is occupied by the activeportion of the thermo-couple. This thermo-couple may be of any standardform and it is encased in a suitable tubular member or bulb 50 whichoccupies the recess and above that in a tube 51 leading to the exterior.The thermocouple casing has a head 52 with a conical under face whichrests on a conical seat 4-? in the plug. Above this seat the plug isinternally threaded. Into these threads I screw a tube which leads tothe exterior of the device and is provided with notches 61 for theapplication of a spanner wrench to turn the tube. The tube thus acts asa nut to clamp the thermocouple casing in place in the plug. The tube 60is properly located near its upper end by a flange collar surroundingthe tube 60 and screwing onto the upper end of the tube 20. One or morevents 28 are made through the tube 20 between the stufiing box nut 31 ofthe collar 70,

The thermo-couple within the casing 50 forms a portion of an electriccircuit which may lead by suitable conductors and 81 (Fig. l) to anindicator in the nature or a voltmeter 82 located at some suitablepoint. The needle 83 of this indicator may be one terminal of a localcircuit Sl leading therefrom through a bell 85 and a battery 86 toanother terminal 87 adapted to be engaged by the needle. Accordingly,when the thermo-couple is sufliciently heated, tne needle 83 swings overto make a contact with the terminal 87, resulting in the ringing of thebell. These electromagnetic elements however, are to be taken as aconventional illustration of any suitable indicator or alarm operated bythe device within the casing 50.

Attention is called to the looseness of the threading of the plug intothe shell, as indicated in an exaggerated manner in Figs. 2 and 5. Thesefigures illustrate the relative position of the threads when thestructure is cold. In normal operation, however, the

expansion of the plug causes this threading i.

engagement to become tight. This peculiar thread engagement is animportant feature of the invention as hereinafter explained inconnection with the description of the operation.

It will be noticed from Fig. 2, that the region of engagement of theplug and shell while within the normal water space is a very materialdistance above the safe low water level. his safe low water levelcorresponds with the level of the bottom of the gauge glass, and theregion of threaded engagement is preferably several inches above thislevel, about three or four inches above it being found mostsatisfactory. This is on account of the following operativecharacteristics.

Due to the rapid ebullition oi? steam in a locomotive boiler, theirregular demand for such steam and the r iclting and plan ()1 theboiler, the layer of saturated ste in immediately above the water,contains so much water in suspensi n that it is a fair conductor of heatand may result in conducting away the heat fron'i region of the alarmcontrol intended to be ot. when such region is located, as ord' justaoove the safe low water level, and prev the operation of. the alarmuntil tl ater lev l l 1 dropped materially below tae safa with thepossibility that it may un -o crown sheet before the alarm is iven.

l have found that although the water level varies greatly in operationof the locomotive, the layer of heavy satvrated hea conducting steam isof approx stant thickness on top of the X .r, cordingly by locating thecontrol-hi1 of the device with reference to the top surface of the layerof heavy saturated. steam,

I obtain a much more accurate resulttha-n where it is spaced withreference to the theoretic sate low water level.

As stated, when the device is installed the threads -11 on the plug seatthe threads 22 in the tube comparatively loosely. N ow, when the boileris heated to normal, the copper plug extending into the fire boxconducts heat from the lire box to the region of these engaged threads,and the expansion oi the plug causes the en agement to become tight.This allows the heat to pass from the plug to the tube, and the water orheavy saturated steam about this region of the tube conducts away theheat so that the pyrometer bulb is not heated to the operating point.

Now, as soon as the water level drops to the bottom of the gauge glass,which is re garder as the danger line, the surmounting layer of heavysaturated steam has dropped below the region of threaded engagement ofthe plug and shell; then the dry steam not able to conduct away the heatfrom the tube, and the body of the tube (which is comparatively thin andhas a much less or Sssectional area than the copper plug) is insui'iicient to conduct heat away from the plug, and accordingly the heatof the latter becomes localized about the pyrometer bulb and increasesin that region. At the same time, heat is transmitted by the tightthreads to the adjacent portion of the shell, which latter expands inthis region, loosening the threads, and such loosening interferes withthe transmission of heat from the plug to the shell. Thus there is astate of thermal equilibrium, where the shell is maintained out of tightcontact with the plug, by such heat as is transmitted and cannot beconducted away, while the plug not being able to dissipate its heatrapidly accumulates heat in this zone, with the result that thepyrometer bulb is heated to the operating point.

Attention is called to the vent from the upper portion of the tubeoutside of the boiler. This relieves any air pressure which might resultwithin the tube, when only dry steam is around the critical region; theloosening of the threads may allow the up ward passage of heated airfrom below the threads of the plug, and, if so, the same tlurther servesin maintaining the heat within the tube and about the upper portion oi"-the plug above the threaded region.

The not result of the peculiar means of suspending the copper plug andthe relative location oi? such suspension, as above described, is thatin normal operation the ahrin act 'ator maintained at a temperaturebelow that which will operate the alarm, but as soon as the water levelhas dropped to the danger region the rising temperature at the criticalregion occurs with great rapidity, insur'ng an almost immediateoperation of the alarm. In tests I have made, under all sorts ofoperating conditions of the locomotive, where the parts were properlyset, the alarm did not operate so long as water was visible in the gaugeglass, but when the water was allowed to descend below that level thealarm invariably operated in less than one minute after the waterdisappeared from the glass.

By reason of the threaded engagement of the plug with the tube, thecritical region may be va led in height as desired by simply rotatingthe plug by the application of a wrench to the lower end. I providesuitable means to prevent the plug unscrewing from the jar of operationwhen the threads are loose. As shown, this comprises a set screw 75passing through the tube 20 outside of the boiler and engaging this tube60, which is screwed tightly into the plug. The parallel threadengagement of the plug enables adjustment not only for difi erent typesoi? locomotives, but for different conditions of operation. Theconstruction of my device is simple; it may be cheaply manufactured; maybe readily installed, and is likewise readily removable for inspection.

Having thus described my invention, I claim 1. The combination, with aboiler, of a metal tubular shell extending upwardly from one wall of theboiler into the normal water space and beyond the safe low water level,a heat conducting plug within the shell secured to the shell in a regionwhich is above the layer of heat-conducting saturated. steam whichoverlies the water when the latter has descended to an unsafe level, andan alarm controlled by concentration of heat in said region.

2. The combination with a boiler having a crown sheet, of a metaltubular shell secured at its lower end to the crown sheet and open tothe the box, a heat conducting plug within the shell extendinginto thetire box and secured adjacent its upper end to the shell in a regionwhich is above the layer of heavy heat-conducting saturated steam whichoverlies the water when the latter has descended to an unsafe level, analarm, and means for actuating it controlled by concentration of heat inthe upper portion of the plug.

3. The combination with a locomotive boiler, having a crown sheet androot sheet, of a metal tubular shell extending from one to the other andopen to the fire box and to the atn'iosphere, a heat conducting plugwithin the shell secured to the shell in a region which is above thelayer of heavy heat-conducting saturated steam which overlies the waterwhen the latter has descended to an unsafe level. said plug being spacedfrom the shell below such region, and an alarm actuatable by the heat inthe plug at such region.

u vi 4. The combination with a boiler equipped with the usual gaugeglass, of a tubular conduit connected to the crown sheet, a heattransmitting plug within the conduit and connected with it in a regionwhich is in the dry steam as soon as the water level has descended belowthe gauge glass, and means whereby the heat in the plug in the region ofsuch connection may eilect the operation of an alarm.

5. The combination with a boiler, of a tubular shell connected to thecrown sheet, a heat transmitting plug within the shell extendingmaterially above the safe low water level, there being a threadedconnection between the plug and shell in a region which is in the drysteam as soon as the water level has descended below the gauge glass,and means whereby the heat in the plug in the region of such connectionmay effect the operation of an alarm.

6. The combination with a boiler, of a tubular conduit leading from thefire box there-of into the water space and adapted to be partiallyuncovered as soon as the water level has descended to the danger level,and a heat conducting plug within the shell and spaced from it, from thefire box' to the region adapted to be uncovered, said plug and shellhaving a threaded engagement above the layer of wet saturated steamwhich overlies the water at said low level, said threaded engagementbeing arranged to become loose when the region of engagement is in thedry steam, and means whereby the excessive heat of the plug in theregion of the threads may operate an alarm.

7. The combination with a boiler, of a tubular conduit leading from thefire box thereof into the water space and adapted to be partiallyuncovered when the water level descends to the danger level, and aheat-conducting plug within the shell, and spaced therefrom from thefire box to the region adapted to be uncovered, said plug having anexternally threaded engagement engaging internal threads in the conduitabove such region, such engagement being loose when the parts are cold.and means whereby the excessive heat of the plug in the region oi thethreads may operate an alarm.

8. In a low water alarm, the combination with a boiler, of a metal shellin the water space and connected with the fire box, said shell having aninternal thread, a heat conducting plug within the shell and having athreaded engagement with it above the safe low water level, and athermo-couple seated in the upper end of the plug and operated byexcessive heat in the threaded region.

9. The combination with a boiler, of a metal tube connected with a crownsheet and in communication with the fire box space, a copper plug withinsuch tube and having a threaded connection with it in a region above thelayer of wet saturated steam which overlies the water at a safe lowwater level, said plug being out of contact with the tube beneath itsregion of connection, the cross sectional area of the plug within thetube being materially greater than the cross-sectional annular area ofthe tube itself, and means whereby excessive heat in the plug in theregion of its connection with the shell may operate an alarm.

10. In a low water alarm, the combination with a boiler, of a conduitconnected with the crown sheet and communicating with the heatingchamber, a heat-conducting plug within the conduit having an externallythreaded portion engaging an internal thread in the shell, a cavity inthe upper portion of the plug leading downwardly to the region withinthe threaded portion, a thermo-couple within such cavity, and an alarmadapted to be actuated by the thermo-couple.

11. In combination with a boiler having a crown sheet and a roof sheet,a metal shell extending from one sheet to the other and threaded intothe crown sheet, a stufling box carried by the roof sheet surroundingthe shell, a heat conducting plug within the shell connected in itsupper region with the shell well above the safe low water level, therebeing means for obstructing radiation directly from the plug to thewater below such region, there being a cavity in the upper end of theplug and a pyrometer bulb occupying the cavity.

12. In combination with a boiler having a crown sheet and a roof sheet,a metal shell extending from one sheet to the other and threaded intothecrown sheet, a stul'ling box carried by the roof sheet surrounding theshell, there being a passageway from the shell above the stufling box, aheat conducting plug within the shell and extending into the fire box atits lower end connected in its upper region with the shell well abovethe safe low water level, there being a cavity in the upper end of theplug and a pyrometer bulb occupying the cavity.

13. In a low water alarm, the combination, with the inner and outersheets of the boiler, of a conduit comprising a bushing threaded fromthe water space into the inner sheet, and a tube tightly connected withthe bushing and extending out through the outer sheet, said tube beingthreaded from its inner end for a considerable distance, and a heatconducting plug having an enlarged externally threaded portion aconsiderable distance above its lower end, said externally threadedportion engaging the threads of the tube, and means affected by anaccumulation of heat in the threaded region of the plug for operating analarm.

14;. The combination with a boiler, of a tube extending from the outersheet to the inner sheet, a heat conducting plug within the tubeconnected with it in a region above the safe low water level, therebeing a cavity in the upper portion of the plug, a pyrometer bulb insaid cavity, and a tube screwing into the upper end or the plug andserving to clamp the pyrometer bulb in place, said tube extendingoutside of the boiler.

15. The combination of a boiler having a crown and roof sheet, a tubularcasing extending through the roof sheet and secured to the crown sheetand having its interior in communication with the tire box space, astutfing box carried by the roof sheet and embracing the casing, acollar on the upper end of the tube, a plug occupying the casing, therebeing a cavity in the upper portion of the plug, a pyroniieter bulboccupying the cavity, a tube extending through the collar and screwthreaded into the upper end of the plug and adapted to hold thepyrometer bulb in place, and an operating connection from the pyrometerbulb extending outwardly through such tube to the exterior of theboiler.

16. The combination of a boiler having a crown and root sheet, a tubularcasing extending through the roof sheet and secured to the crown sheetand having its interior in communication with the fire box space, astufling box carried by the roof sheet and embracing the casing, a plugoccupying the casing and extending down into the fire box and thereprovided with an angular head, said plug having an elevated enlargementexternally threaded and engaging internal threads in the casing therebeing a cavity in the upper portion of the plug, a pyrometer bulboccupying the cavity, and an operating connection from the pyrometerbulb extending outwardly to the exterior of the boiler.

17. The combination with a boiler, of a tubular shell connected to thecrown sheet, a heat transmitting plug within the shell extendingmaterially above the safe low water level, there being a threadedconnection between the plug and shell above such level, which connectionis adapted to become loose when dry steam surrounds such region, meanspreventing the plug being inadvertently displaced when the threads areloose, and means whereby the heat in the plug in the region of suchconnection may effect the operation of an alarm.

18. The combination of a boiler having a crown and roof sheet, tubularcasing extending through the roof sheet and secured to the crown sheetand having its interior in communication with the fire box space, astuffing box carried by the root sheet and embracing the casing, a plugoccupying the casing and extending down into the fire box, said plughaving an elevated enlargement externally threaded and engaging internalthreads in the casing which are adapted to become loose when thethreaded region is surrounded by dry steam, means to prevent the pluginadvertently unscrewing when the threads are loose, and an externalalarm operated by excessive heat in the threaded region of the plug.

In testimony whereof, I hereunto afiix my signature.

R. L. BADGER.

